1. Field of the Invention
The invention covers the mining industry and can be used by ore underground mining, in particular, for mining metallic deposits including native metals. This invention relates to a method for detection of an occurrence zone of a diapir finger, a mantle substance saturated with native metals.
2. Description of the Related Art
Rifting zones exist on our planet. These zones are located in the oceans (mid-ocean ridges, Iceland), on the continents (Baikal, Africa, Jordan river—Dead Sea, Suez, Western Canada et al.) and under the continents (west of USA).
All riftzones are banked up by diapirs (brows) of the abnormal mantle from below. Diapirs go up to the depth of about 35 km under the continents and at a distance of about 1.5 km from the bed of rift valleys in the oceans. Diapirs are characterized by reduced density and rates of the transmission of seismic waves as compared with a normal mantle.
In some places the diapirs penetrate by their “fingers” from the 35 km depth into the overlying rocks up to the depth of approximately 3-10 km. The “fingers” outgoing from diapirs have abnormal conductivity (105-106 times as much as the conductivity of silicate rock) and are represented by intermetallic compounds (silicides) and alloys on the basis of Si, Mg, Fe (silicon, magnesium and iron).
The reaching of fingers by any up-to-date methods (drilling, underground opening, open cut drilling) will allow for mining of native metals. Traditionally, the metals are obtained from compounds (oxides, sulfides and other) with large power inputs necessary for breaking the molecular bonds of the compounds.
In this case it is essential to locate a mining place, i.e. to detect the location of a diapir finger containing silicides and alloys. This place can be determined taking into account trendlike properties inherent in diapir fingers of the mantle substance.
A method for detection of zones in the earth's crust possessing an increased conductivity (magnetotelluric sounding method) is known. Example: “DEEP REGIONAL RESISTIVITY STRUCTURE ACROSS THE BATTLE MOUNTAIN—EUREKA AND CARLIN TRENDS, NORTH-CENTRAL NEVADA” by Brian D. Rodriguez and Jackie M. Williams, Open-File Report 01-346 on-line edition, 2001.
The disadvantage of this method is expressed in the fact that the abnormal conductivity is traditionally related to the presence of graphitization zones and/or hydrothermal solutions but not to the presence of fingers of intermetallic diapirs by interpretation of data obtained by use of this method.
A method for detection of blocks in the earth's crust possessing increased rates of seismic waves (reflection method) is known by the Consortium for Continental Reflection Profiling (COCORP).
The disadvantage of this method is expressed in the fact that the high velocity blocks are not related to the presence of silicide diapirs in the higher levels of the earth's crust by interpretation of data obtained by use of this method.
The methods for detection of blocks in the earth's crust characterized by locality and high activity of magnetic anomalies and low-amplitude anomalies of a gravity field (gravimetry and magnetometry) are known. Example: “Gravity and Magnetic Study of the Pahute Mesa and Oasis Valley Region, Nye County, Nevada” by Edward A. Mankinen, Thomas G. Hildenbrand, Gary L. Dixon, Edwin H. McKee, Christopher J. Fridrich, and Randell J. Laczniak, Open-File Report 99-303.
The disadvantage of these methods is expressed in the fact that active magnetic anomalies are not related to a transitional area from silicides to silicates in apical parts of silicide diapirs, and anomalies of a gravity field are not related to the presence of silicides by interpretation of data obtained by use of these methods.